Method of preparing paper for bending



Sept. 26, 1939. H. B. ALLEN 2,173,927

METHOD OF PREPARING PAPER FOR SENDING- Filed Feb. 24, 1937 v remainder of the Patented Sept. 26, 1939 UNITED STATES METHOD OF PREPARING PAPER FOR BENDING Harry B. Allen, Rochester, N. .Y.

Schaefer Mounters, Inc.,

notation of New York i Application February 24 1 Claim.

My present invention relates to the art of paper manufacture and more particularly to. the art of blanking heavy paper, cardboard and pulp board in such manner that it will bend along a desired 5 line'without breaking. This is familiarly done, as

in paper box manufacture, by perforating, semiperforating or simple scoring but, in such usage, the bending line need be strong enough only to survive and sustain itself when bent once into the permanent shape. In the matter of other paper products made of paper board, such as the heavy signs used in window display, a 'morepermaneht and serviceable fold or hinge must be provided that will stand bending back and forth'withont fracture or cleavage. This repeated articulation accompanies processes of manufacture, involving printing, lithographing and other treatments, and also shipping, erection and frequent temporary foldings and 'resettings of the signs or displays.

Heretofore, the practice has largely been, with respect to window displays, particularly, that of simply scoring or slitting the board and reinforcing it along the scored line with a definite hinge element in'the form of a strip of -a better quality of paper or with fabric. This not only disturbs the continuity of the surface as a matter of appearance but interferes with printing and lithographing because the hinge element does not take the treatments in the same manner as the board, and it adds to the expense.

My invention has for its object to furnish a hinge for this general purposein a paper board and a method of producing the same, which hinge formation requires no additional material, does not perceptibly interrupt the evenness of the sur-' face of the board, being practically undiscernible,

and is one that will withstand repeated bendi'ng back and forth along a definite'line. To these and 40 other ends, the invention resides in certain improvements and combinations of parts, all as will be hereinafter more fully described, the novel features being pointed out in the claimat the end of this specification.

In the drawing:

Fig. 1 is a plan view of the face of a sheet of cardboard or pulp board provided with a hinge constructed in accordance with. and illustrating one embodiment of my invention; v 5Q Fig. 2 is a similar view of the reverse side;

i Fig. 3 is an "enlarged transverse section through the hinge portion with the board in the normal or 'flat condition of Figs. 1 and- 2;

Fig. 4 is a similar view with the board bent at 5 right angles at the hinge line;

assignor to Webster, N. Y., a cor- 1937, Serial No. 127,4 (0]. 92-70) Fig. 5 is a similar view with the boardgdoubled upon itself at the hinge line; v

Fig. 6 is a sectional view on the scale of Figs. 3 to -5 of a form or die couple that may be used according to my method in producing the hinge, 6 and Fig. '7 is a view similar to Fig. 6 showing the behavior of the work in the operation of the die couple. a x

Similar reference numerals throughout the several views indicate the same parts. j

This applicatiofi is a continuation in part of my pending application, Serial No. 83,097, filed June 2, 1936. a v 1 Referring more particularly to the drawing and 5 assuming that the article shown in Figs. 1 and 2 is either a. hinge element per se or represents a. useful paper manufacture that it is desired to bend along the general line A-A, l and 2 indicate the hinged parts of fiber board, in a continuous' integral piece. Though not necessarily, it is preferably provided on its obverse side, and usually is, with a facing lamination 3'of relatively thin glazed or other ornamental paper or one of better. adapting the article to printing or lithographing. In the practice of my invention,, I place the board or article within a'die couple, shown in Figs. 6 and 7, consisting of an upper male element M and a lower female element F. 3

The latter is provided with asharp shouldered groove F constituted by the separation of the edges of face plates F"thereon, it being clear, of course, that these two figures are greatly enlarged and otherwise proportioned to clearly bring out 35 the mode of operation. The die action is purely reciprocatory and the upper male die is provided on its underside with a continuousstraight edge knife blade M of somewhat the nature of a printer's rule-in fact, it isitself called a rule. This is 40 centered along the median line of the groove F and its stroke is such that, in practice on average .material, the cutting edge will travel to within about twelve thousandths 'of the bottom of the groove.

The board is placed on the face plates with the obverse surface 3 undermost or toward the, grooved die element. It is not necessary in all cases that these elements meet or even substantially meet to press the expanse of the paper during the cycle. When the male die descends,-it thus cuts through substantially the entire thickness of the board, except that it functions as a punch as well as a cutter and forces, regionally, the underside strata of the pulp into a rounded a texture 25 appears 'in Fig. '7.

A formation, shown in Fig. 3, results in the board. The knife M produces a sharp clean slit 4 in the upper side without'otherwise disturbing the continuity of its plane surface, which slit extends partially through the sheet, bending the adjacent fibers inwardly and downwardly, as indicated by the fine lines 5. In fact, as just above stated, the knife edge travels practically from the plane of the upper surface of the board to the plane of the lower surface of the board, but does not entirely sever it. The pressure or resistance of the knife compresses the remaining fibers, together with the adjacent portion of the facing 3, so that theybulge, with the one operation, into the groove F along the line of cleavage. The fiber layers as deposited by the paper making machine, or the laminations of a composite or built-up board, will bend but not be broken and the uncut strata in. continuation of 5 are simply looped around the cut, 'as indicated at 6. The result is a semi-cylindricalrib I with sharply de-, fined imperfora-te shoulders that is raised on the obverse side and which may be described as constituting a pintle of the resulting hinge. The turning axis 8 is in the region of the bottom of the slit. As illustrated in Figs. 4 and 5, respectively, when the parts I and 2 are relatively partially folded or completely folded, the shoulders of this rib'orpintle furnish two points or lines 9 upon which the fibers of the board can give, as well as the third line 8, along the bottom of the cut. The fibers are thus subjected to a tensile strain distributed over quite an area instead of an abrupt transverse strain concentrated on one line.

' It is a well known fact that the tensile strength of paper is very high, whereas its resistance to transverse strains is comparatively low. With the conformation within the groove F, as clearly.

conversion of the application of forces from the latter condition to the former, a hinge results that permits the board to be bent a great number of times without cracking or breaking or even becoming disfigured.

This invention is to be distinguished from prior practices in the art, in which slitting of this general nature is almost invariably accomplished with the use of rotary disk knives. These are wholly.

useless for present purposes, because it is force exerted by the flatwise pressure of a straight edge knife that, in my method, serves to punch out the rib in the one operation simultaneously with the slitting. The resulting article, as clearly appears in Fig. 3, has on one side a semi-cylindrical rib 'l with the sharp shoulders at 9 produced by the die as bending points, while the opposite side of the board is fiat and continuous except for the minute line of the slit 4, which is hardly noticeable when closed. The plane of the surface is not disturbed for the reception of printing other similar treatments.

I claim as my invention:

A method of ribbing and scoring paper pulp board and the like to provide a durable hinge line, which embodies applying fiat parallel pressure with a sharp straight-edged knife against one side of the board and thereby thrusting it into a wider female member on the opposite side until a rib has been extruded from the board to project from the latter side, all without appreciably cutting the fibers of the board on the first mentioned knife side, supporting the rib against further extrusion andcontinuingthe same action of the knife to partially slit the rib, the extruding and slitting resulting sequentially from one movement of the one knife.

HARRY B. ALLEN. 

